1. Field of the Invention
The present invention relates to an electric storage device having an ion source for supplying ions to an electrode mixture layer.
2. Description of the Related Arts
There have been proposed a lithium ion battery or lithium ion capacitor as an electric storage device mounted to an electric vehicle or hybrid vehicle. An electric storage device has been proposed in which a metal lithium foil and a negative electrode are electrochemically in contact with each other in order to enhance an energy density of the electric storage device. Since the metal lithium foil and the negative electrode are brought into contact with each other as described above, lithium ions can be doped beforehand into the negative electrode. Thus, the potential of the negative electrode can be lowered, and the capacitance of the negative electrode can be increased. There has also been proposed an electric storage device having through-holes formed on a positive electrode current collector or a negative electrode current collector in order to smoothly dope lithium ions into the laminated electrodes (see, for example, JP-3485935).
The lithium ions emitted from the metal lithium foil move to the negative electrode via an electrolyte solution. Therefore, when the amount of permeation of the electrolyte solution to the electrode laminate unit varies, the amount of the lithium ions to be doped also varies. Further, small electric current flows to the metal lithium foil from the negative electrode when the lithium ions are doped, so that the lithium ions move from the metal lithium foil toward the negative electrode with the flow of the small electric current. Accordingly, when the current density at each part of the negative electrode varies, the amount of the lithium ions to be doped also varies. The variation in the amount of the lithium ions entails the variation in the potential of the negative electrode, as well as local overcharge or over discharge. Thus, the variation in the amount of lithium ions deteriorates the electric storage device.